Who has gutted main cats?

[sempaipaul]

Anyone on here?

Currently my pre-cats are gutted and since I have every thing torn apart I figured I might as well do this now.

I don't particularly want to go to downpipes because I'd like to retain the factory appearance as in MD as part of bi annual emissions they peek under the car with a glass mirror. The way they test for emissions however is by simply logging into the OBD port. Currently with my precats being gutted and coded out I have had no issues passing. I have a Revo chip and wonder how difficult it would be to code out the main units.

I anticipate I'd get a few ponies and an even better sound with my milltek non-resonated.

Thoughts?

Thanks
Paul

[hahnmgh63]

Revo tune has been know to run lean, not as lean a GIAC but lean enough to worry if you run it hard. I had Revo a few years back, at the time only Revo, APR, and GIAC had tunes but nowadays you have many choices. Revo will not code out the rear O2 sensors so you will need a custom tune. There are many tuners that will code out the rear O2's but I would be careful as some had readiness issues so see if anyone in your area chimes in and/or ask some of the tuners: Eurocharged, 10secmarc, AMD, etc...

[sempaipaul]

Revo tune has been know to run lean, not as lean a GIAC but lean enough to worry if you run it hard. I had Revo a few years back, at the time only Revo, APR, and GIAC had tunes but nowadays you have many choices. Revo will not code out the rear O2 sensors so you will need a custom tune. There are many tuners that will code out the rear O2's but I would be careful as some had readiness issues so see if anyone in your area chimes in and/or ask some of the tuners: Eurocharged, 10secmarc, AMD, etc...

Thabks for your feedback.

so currently my "little" initial cats are gutted and I assume the O2's that are in the big main cats are coded out as I have no CEL. I wouldn't need to code anything else out, right?

Who hi are the primary custom tuners out there? I anticipate getting a custom map may be best instead of all the shelf items available from revo, apr, etc.

thanks
Paul

[lswing]

Thabks for your feedback.

so currently my "little" initial cats are gutted and I assume the O2's that are in the big main cats are coded out as I have no CEL. I wouldn't need to code anything else out, right?

Who hi are the primary custom tuners out there? I anticipate getting a custom map may be best instead of all the shelf items available from revo, apr, etc.

thanks
Paul

I'm guessing that having the pre-cats gutted isn't enough to mess with those rear O2's. Keep in mind, gutting those main cats is a PAIN, 6-8 hours I've heard depending on power tools.

Mark mentioned the tuners, ask some of the indy tuners: Eurocharged, 10secmarc, AMD, etc...maybe 034.

You could easily check with VCDS to see if they are coded out I would think, just go look at the numbers for your O2's, and if coded out I would think it would be 0.

[SteveKen]

I'm guessing that having the pre-cats gutted isn't enough to mess with those rear O2's.

I'm pretty sure it does and has to be coded out.


Keep in mind, gutting those main cats is a PAIN, 6-8 hours I've heard depending on power tools.



If you have your own tools to do the necessary cutting and welding, it's just as easy to cut off the cats and dissect them and insert an interior straight pipe inside the bodies then re-weld everything back together. I can't attest to the RS6, but on the NA 4.2, gutting just the cats makes the exhaust sound terrible due to the turbulence that happens when the exhaust hits the empty cavity.

[makaveli42]

I don't have any cats or resenators. sounds mean as can be and runs fine. Had my tuner code out the o2s and installed a wideband to make sure it's not running too lean/rich.